Encapsulating die roll system



Sept. 8, 1959 sTlRN ETAL 2,902,802

ENCAPSULATING DIE ROLL SYSTEM Filed Dec. 24, 1956 1 2 Sheets-Sheet 1INVENTOR. FRANK E. STI RN BY ARTHUR S. TAYLOR Sept. 8, 1959 F. E. STIRNETAL ENCAPSULATING DIE ROLL SYSTEM 2 Sheets-Sheet 2 Filed Dec. 24, 1956INVENTOR.

FRANK E. STIRN ARTHUR S. TAYLOR United States Patent" (3 ENCAPSULATING'DIEROLL 'SYSTEM Frank Stirn,-Mnsey, and-Arthur S.'"Ta"ylor, SpringValley, 'N.'Y.', assignors rtoiAmericane 1Cyanamid Company, New York, N.Y.', a corporationof Maine ApplieationiDecember 24; 1956, Serial No.630,345

6 Claims. ..(Cl.. 53-1-28)? Thi's inventionrelates to a sealing rollsystem for use in forming and fillingsoft plastic capsules fromi'aplastic" strip,"and more particularly'to (l)'a die roll in which 'thecutting out' rims reciprocate'in. the die-roll, so as'to be flush duringthe filling step, and which rise to cut through: the plastic strips inthe cutting out step, and (2) a flexible metal belt serving as thesealing member acting against cutting out rims on a die roll."

It is an object of this invention to'providea method,

and a machinefor practicing the method, whereby "a ma terial. to beencapsulated, which "may be a powder, a liquid, or a paste, is filledinto cavities formed in a de formable' plastic strip,fwhi'ch strip isprevented 'from slidingover cutting out rims .during the forming,fi1l'ing,'.

and cutting out and sealing operations.

It is another object of this invention to provide" a cavity die rolliniwhich the vacuum under a plastic strip is maintained withoutexcessive leakage.

It is a further. object of. this inventionuto provide a dieiroll which:gives uniform support to a plasticstrip between capsule formingcavitiesdui-ing the fillingopera tion'.

It is :a yetfurther object of .thi'sinventiontoprovide a cavity die rollwhich prevents theplastic "stripjfrom'walk-f ing on thesurfa'ce "of said"roll? It is an additional object of this inventionto provide a cavitydie roll of'simplified'constructioni It is -aparticular'objectof'thisiinvention to providea very*low a n gleofconvergence betweenthe"cover'plastic strip and thelower cavitiedplasticstripin'a capsule form ingoperation':

n isa specificobject'of'this inventiontwprovide a searoll----system-*which eliminates-the necessity for accurate mating ofcooperating sealing membersjand inwhich'the inherent flexibilityof'tdesign expeditiously compensates for-"minon'dimensional errors inconstruction andflnis eliminates the necessityforhighprecision machine W0I'k.'

Tlieart-has' long'used cooperatingmatingseal rolls in symmetricsystemsfor the manufacture of' capsules? Re cently asymn'ictri'c 'die' "roll'jsystems-have beenintroduced i in which a smooth'surfacesealroll-eontactsa cavity die f roll-such as,"for example-,shownin'UESQPa'tent 2,663,128,

Stirn' and Taylor; -Metho'd"and'-'Machine'for Making Cap sules';December-22; In such systemsnheangleof convergence between' 'the upper*and lower plastic strips;

has-been deterinine d 'by the diameters of the cavity die" roll-andtheseal roll? A reduction in'this angle has re convergeneeristoo'great,*the strip" tends-'towalkor weave" on the" surface'of the"cavity die *rol1;and the'seal "ofthe strips to each 'bther is impairedbecause the leading "edge and '--the? -trailing"edge of" the cutting-outrims. operateiat" a different"angle ofzittackthahth side edges?Obviously if the cutting --out rirn'- comes down symmetric and'p'erpendic'ulai to' the fil'rii's -atzthe 'tinie 'of' sealingyand advan tageousseal is accomplishedr-With fixed edgesand r'ol'ls' this is not'possibleiBu't largersizes of *rollshave been used: tonminimizer the anglemf-eonvergencei For con- 2,902,802 Patented. Sept. :8, 1959 ICCvenience-in operatiomandto reduce the size ofthe maobtainedvwithsmallerrolls is desirable.

chine a system inwhich a smaller convergence angle is- Further theplastic w strip slides overthe surface of the cavity die. rollandover'the cutting outrims on that-- This problem has been common to alldie rolls die roll. in which outstanding. cutting out rims are necessaryfor the cutting out andsealing operations.

These difiicultiesare largely obviated by the present machineinLWhich-theproblems introduced by the-out-- standing cutting out rims areobviated by using a hollow die roll havingin its surface a plurality ofcavity slides:

havingcutting out rims thereon, which-rims are retracted so as to beflush with the surface of: the die'roll during-m;

the initial :plastic strip-positioning, cap'sule cavityforming,.and.capsule cavity filling operations, and in which" cutting:outrims. on the cavityslides 'areforced up through,

the plastic strips after the upperstrip" which covers the." capsulecavitiesis inplace. Such a die 'roll maybe 'useda in the presentnovelnmachine orusubstituted in conven--- tional encapsulation machines.

The. sealing member is a flexible belt, preferably of' metal. The beltis supported-on pulleys and is forced against-the seal roll by tensioniii-the belt. Belt tension is used to hold the belt against the'cutting=out'rims,'.-but yet not deform these cutting out n'ms or squashthe plastic strips. One. of the support rollsrnay be positioned inrolling contact, throughthe belt, with the cutting out-rims? to giveincreased sealing-pressure at the point of final seal.

Because of the inherent flexibility of a belt, any minor variations intheworking surface of the cutting-out rims: due towear of these'rims andanyminordeviations from strict parallelism of: the-die roll and the beltsupport rolls as'well as any play in the cavity slides are inherentlycom--- be referredto as the upper and lower: plastic strip -with--- outfurther specifying its characteristics as such strips are" Well-known inthe art. Substitutes may, of course, 'be used. fo'r gelatinand for theplasticizer, depending upon tern-=- p latu'le stabilityrequirements,edibility, costs, etc.-

The plastic strip maybe cast by a machine such as de k:

scribed in US. Patent 2,663,128, aforementioned, and the filliiig' ofthe formed capsule forming cavities may be as:

described in saidpatent or as described in U.S. Patent. 2,775,080,FJEfStirn et al.-, Method of Forming PoWder-. I

and-Liquid-Fille'd Capsules, dated December 25, l9S6,-or-

U.S'..".'Pa"tent 2,690,038fFJ'E. Stirn et al., Liquid-Filled Capsule"FormingMethod and Apparatus, September 28,

1954", "oras otherwise known to those skilled in theart.

The formation of the strip, filling of the formed capsuleformingcavities, and.the pre-treatment of the strip, and

the"disposition of the'capsules after they are formed and'cut out arenot here described as these steps are known to those skilled in the artand donot form novel elements of the'present invention.

Other-objects and" advantages ofthis invention will appear'from adescription of certain specific embodiments thereof 'and' asshown in theaccompanying drawings:.

Figure l is an elevation, in section, of the seal roll sys,-.

tem" showing the dieroll and seal belt. 7

Figure 2 is a section on line 22 of Figurel showing a cross section 'ofthe die roll system.

Figure'3 is a view'of a portion of the face of the die...

Figure 4 is a face view of the valve plate.

Figure 5 is a view of a modified construction, with a conventionalcavity die roll, cooperating with a long sealing belt.

The size and shape of the desired capsule determine the size and shapeof the capsule forming cavity and the cavity slide. The capsules may beround, elliptical, or long oval or other desired size and shape. Thefigures show a long oval form, which is particularly popular with themedical profession.

The plastic strips may be interiorly coated with a protective materialto prevent the contents of the capsules from deleteriously aifecting theplastic strip. The die roll and seal belt contacting sides of theplastic strips may be coated with a thin layer of a lubricant such asdeodorizedv kerosene, such as described in US. Patent 2,674,073, Tayloret al., Relieved Nonskid Seal Roll and Method of Use, April 6, 1954.

Lower plastic strip 11, supplied from a suitable source, is fed onto thesurface of a hollow die roll 12, mounted on a support shaft 13,journalled in a main frame 14, by shaft bearings 15. The support shaftand hollow die roll are driven by the die roll drive gear 16 driven bysuitable conventional means, which are not shown.

In the hollow die roll are a plurality of radial apertures 17 in each ofwhich is a cavity slide 18 having at its outer end a capsule formingcavity surrounded by a cutting out rim 19. At the other end of thecavity slide is a cam surface 20 which slides on the cam 21 and is heldagainst the cam by the slide return springs 22. A small toe on the frontand rear of the slide near the cam surface furnishes a bearing area forthis spring.

The cavity slide is supported by the cam so that the cutting out rim isflush with the outer cylindrical surface of the hollow die roll as thelower strip is fed onto that surface, and as the strip is drawn into thecapsule forming cavity in the end of the cavity slide by vacuum actingthrough the slide gas orifice 23, and the slide gas passage 24, which inturn are connected to the die roll manifold 25, which extends to thevalve plate face 26 of the die roll.

Resting against the valve plate face of the die roll, and held inposition thereagainst by vacuum is the valve plate 27. In this valveplate is a vacuum chest 28, the lower portion of which forms a balancingchest to aid in holding the valve plate against the valve plate face ofthe die roll, in which valve chest the vacuum is introduced by a vacuumlead 29, leading to a conventional vacuum source. Also in this valveplate is an atmospheric chest 30 vented to the atmosphere by anatmospheric vent 31,

to permit atmospheric pressure to act in the capsule forming cavity inthe cavity slide at the time of seal as is later described. Also in thevalve plate is a gas pressure chest 32 in which pressure is maintainedby a gas pressure lead 33 leading to an external gas pressure source,not shown, which gas pressure is used for ejecting the capsule as islater described. The gas supplied to the gas pressure chest may beheated, as described in US. Patent 2,697,314 Stirn et al., Heating DieRoll, December 21, 1954, to maintain the die roll and cavity slides at adesired temperature.

As the die roll rotates, vacuum acting through the vacuum chest, dieroll manifold, slide gas passage, and slide gas orifice reduces thepressure under the lower plastic strip 11 and draws the plastic stripdown into the cavity slides, as shown at cavity slides U, V, W, and X,thus forming strip-lined cavities. The strip lies flat on the face ofthe seal roll. With raised cutting out rims, air can leak into thesystem adjacent to the rims, and greater vacuum capacity is required toallow for such leakage. With the present system there are no raised rimsand leakage is minimized.

The strip-lined cavities are filled with the material to be encapsulatedby a filling head 34. This filling head may be one of those described inthe aforesaid US. Patbelt 39, which seal belt runs over an upper sealbelt support roll 40, which in turn is journalled in the upper supportroll bearings 41 and positioned in the frame by the upper bearingpositioning screws 42. The tension in the seal belt is controlled byadjusting the roll position by these screws. The belt supported upperplastic strip is brought down to and in contact with the lower plasticstrip containing the filled capsule forming cavities.

In as much as this belt is fiat before it reaches the point of tangency,the upper plastic strip is a plane, and the angle of convergence of thetwo strips is determined solely by the single die roll. Thus the angleof convergence is markedly less than would be the case with two rolls,all convergence problems are associated with only the one lower strip.Additionally, there are no raised cutting out. rims at the time ofconvergence, and problems associated therewith are deferred until thestrips are more firmly positioned between the seal belt and the dieroll.

Just before the upper plastic strip covers the capsule forming cavitiesin the lower plastic strip, the die roll manifold passes from contactwith the vacuum chest to contact with the atmospheric chest in the valveplate, which permits the natural elasticity of the lower plastic stripto cause the strip to start to rise and thus diminish the volume in thecapsule forming cavity in the lower plastic striy. The angular positionof the valve plate is such that all excess air in each capsule formingcavity escapes just as the upper plastic strip comes in contact with thelower plastic strip and closes 01f communication with the outside air.Any minor variations in quantity of fill caused by mechanical variationsin the sizes of the various parts is compensated at this point, as thecapsule contents are so much more viscous than air that the contentswill not escape at the bite of the roll, but only the air will escape,thus giving completely filled capsules without trapped air bubbles.

The two plastic strips are firmly held between the face of the die rolland the seal belt. This prevents loss of capsule contents, or sliding ofthe strips during the sealing and cutting out steps. Moreover, thestrips are in contact and well supported at the time of cut out andseal, so that the entire periphery is sealed and cut out simultaneouslyso there is no leading or trailing edge, with associated problems.

As the die roll rotates the cam surface of the cavity slide slides onthe cam 21 which is held against rotation by the cam holding plate 35which in turn is positioned by the cam plate positioning shaft 36 whichcauses the cam to remain stationary on the cam bearings 37 as thesupport shaft 13 rotates. The cavity slides are raised by the cam asthey pass through positions D, E, and F to a final height at position Gso that the cutting out rim is forced up through the lower and upperplastic strips. As the cutting out rim passes through the two plasticstrips, that portion of each of the plastic strips which surround thematerial being encapsulated are cut out and sealed to each other.Because of the plastic flow and sealing characteristics of the plasticstrip the separate cut outs are joined thus forming the capsules, andleaving behind the perforated strips or web. The lower seal belt supportroll 43 journalled in the lower support roll bearings 44 is positionedby the lower bearing positioning screws 45 so as to hold the seal beltagainst the cutting out rims and thus insure perfect cutting out.

This causes not only the flexible pressure from tension in the belt butpositive positioned pressure from the lower support roll to function toinsure the cut out.

.The cut out plastic; s tripsare then separated from thus formedcapsules, which capsules are still retained in the cavity slides."Conveniently the cutting outstrip may be held against the die rollduring the removal of the capsules.

The upper plastic strip is advantageously at a slightly warmertemperature than the lower plastic strip so that the seal line betweenthe two portions of each capsule is caused to become equatoriallyadjusted, by the warm portion from the upper strip stretching, and thecooler portion from the lower strip shrinking, such as is describedinlthe aforesaid Patent 2,663,128.

The temperature adjustment is conveniently obtained by positioning anupper seal roll heating plate 46 against the upper seal belt supportroll 40. A heating plate heating element 47 is incorporated in the upperseal roll heating :plate, which may conveniently be an electricresistance element, and the energy input is controlled by a :heating'.plate thermostat 48; The heater leads 49 and the thermostat leads 50are fastened to a conventional control system, and energy source.

As the die roll rotates the capsules are ejected into the capsulereceiving shield 51. The ejection is' in part caused by gas pressurethrough the pressure chest 32, acting through'the die roll manifold 25,slide gas passage .24 and slide gas orifice 23. The ejection is aided bya rotating stripper 52 which is a flexible bladed element h'aving bladesof soft rubber or flexible cloth, or brush :bristles,'wh:ich aids inpicking up the capsules and knocking them out of the capsule formingcavity in the cavity slide into the capsule receiving shield. As thecapsules fall :to the lower portion of the shield, they are picked up byconveyor air blastj53 and blown through a capsule conveyor 54 forfurther processing. The residual web 'is pulled off by conventionalmeans at the web take off 55, and recovered for reuse, or otherwisedisposed of. i Modifications As will be obvious many variations can bemade in the machine within the scope of the present invention. Forexample, the die rolls and the support rolls are conveniently of brassto insure high heat conductivity and ease of manufacture, and thecutting out slides are conveniently of steel for hardness, while thesealing belt itself is conveniently of stainless steel for bothcorrosion resistance and strength although other flexible durablematerials may he used. Other materials of construction may be used. Thebearing journals and support systems may be modified within wide limits.For instance the die roll may be journalled on a fixed shaft. Preferablythe cam and die roll are supported and positioned by cantilever shafts,so that the front surface of the roll is open to the operator for easein inspection and in threading during starting up and shutting downoperations.

As shown in Figure 3 the die roll may contain four rows of cavity slidesbut, of course, any convenient number may be used. Similarly, the dieroll is shown with 24 cavity slides in a peripheral row. A larger numberis conveniently used as a larger number renders the sides of adjacentslides more nearly parallel, and reduces web losses. Less than 24 wouldbe more convenient for small runs, or experimental use.

As shown in Figure 5 a conventional raised rim cavity die roll 56 may beused in conjunction with a seal belt 60 with the many advantagesaccruing from the reduced angle of convergency, and the flexibility of aseal belt as contrasted 'With a solid seal roll. As shown in Figure 5,the upper belt support roll 57 may be fixed in position, with anadjustable lower support roll 58, the position of which is controlled bypositioning screws 59. This relationship with the seal roll permitsadditional flexibility of the seal belt. Because the lower support rollis not in contact through the belt with the cutting out rims on the dieroll, the problems of uneven wear, or minor mechanical variations inconstruction are well tolerated.

6 The tension in the seal belt is adequate to insure adequate out out.

Theoretically, only the cutting out rim need rise during the cutting outand sealing step. Using a die roll in which only the rim raises has thetheoretical advantage of leaving the capsule forming cavity volumeconstant, but introduces complications in design because of a fixed plugin a moving cylinder, which in the space available causes constructionproblems. Also important'is the desirability of reducing interior movingparts which can become clogged up with strip fragments. The use of solidslide inserts simplifies such construction.

Whereas air pressure is normally adequate for ejection of the capsule,positive piston action of the type shown in Patent 2,775,080 may be usedin each slide. With thin plastic strip, the strip may tend to be drawninto the slide gas orifice. The use of felt inserts, such as describedin our copending application Serial No. 474,801, Die Roll forEncapsulating Machine filed December 13, 1954, now US. Patent No.2,799,048, in the gas orifice controls the plastic strip, even if verythin.

The retraction of the slides in the die roll may be accomplished by'camaction instead of springs, or the cavity slides may be retracted by amagnetizedcam, such as described in US. Patent 2,775,084, 'Stirn et al.,Apparatus for FillingPowder in Capsules, December 25, 1956. Similarlythe valve plate may use springs or magnetic inserts to aid in holding itagainst the valve face of the die roll, or other shapes of valvesurfaces may be used.

Other modifications of the present novel die roll and seal belt systemare within the scope of the following claims.

We claim:

*1. A cavity die roll for forming soft plastic capsules from plasticstrip which comprises: a hollow die roll having a series of aperturesextending from the Working face into the hollow interior thereof, meansfor rotating said die roll, a cavity slide having a capsule formingcavity and (a cutting out rim .at the outer end and a cam means at theinner end in each aperture, and a stationary cam, acting on the cammeans of said cavity slide, of such configuration that the slides arepositioned with the cutting out rim about even with the surface of thedie roll during a loading portion of a capsule forming cycle, and withthe cutting out rims raised against a sealin means during a cutting outportion of capsule forming cycle.

2. A cavity die roll for forming soft plastic capsules from plasticstrip which comprises: a hollow die roll having a series of aperturesextending from the working face into the hollow interior thereof, avalve plate face on said die roll, a die roll manifold from the valveplate face to said apertures, means for rotating said die roll, a cavityslide having a capsule forming cavity and a cutting out rim at the outerend and a cam means at the inner end in each aperture, said slide alsohaving a slide gas passage in cooperating relationship with said dieroll manifold, and a slide gas orifice opening into the capsule fonningcavity in said cavity slide, a stationary cam, acting on the cam meansof said cavity slide, of such c0nfiguration that the slides arepositioned with the cutting out rim about even with the surface of thedie roll during a loading portion of a capsule forming cycle, and withthe cutting out rims raised against a sealing means during a cutting outportion of capsule forming cycle, a valve plate positioned against thevalve plate surface of said die roll having therein a vacuum chest, tanatmospheric pressure chest, and a pressure chest, in such angularposition as to draw a plastic strip into the capsule forming cavity andhold the strip in the cavity during a loading cycle, release the stripin time to eject surplus air before a cover strip is juxtapositioned,and eject the capsule after its formation, and a vacuum lead, anatmospheric vent, and a pressure lead, respectively, to said chests.

3. A sealing roll system for forming soft plastic capsules from plasticstrip which comprises: a hollow die roll having a series of aperturesextending from the working face into the hollow interior thereof, meansfor rotating said die roll, a cavity slide having a capsule formingcavity and a cutting out rim at the outer end and a cam means at theinner end in each aperture, a stationary cam, acting on the cam means ofsaid cavity slide, of such configuration that the slides are positionedwith the cutting out rim about even with the surface of the die rollduring a loading portion of a capsule forming cycle, and with thecutting out rims raised during a cutting out portion of capsule formingcycle, supporting rolls for a flexible belt, and a flexible belt on saidpulleys, in cooperative relationship with said die roll, so as to retaintwo plastic strips therebetween, and cooperate with said cutting outrims to cut out capsules from the plastic strips.

4. A sealing roll system for forming soft plastic capsules from plasticstrip which comprises: a hollow die roll having a series of aperturesextending from the working face into the hollow interior thereof, avalve plate face on said die roll, a die roll manifold from the valveplate face to said apertures, means for rotating said die roll, a cavityslide having a capsule formin cavity and a cutting out rim at the outerend and a cam means at the inner end in each aperture, said slide alsohaving a slide gas passage in cooperating relationship with said dieroll manifold, and a slide gas orifice opening into the capsule formingcavity in said cavity slide, a stationary cam acting on the cam means ofsaid cavity slide of such configuration that the slides are positionedwith the cutting out n'm about even with the surface of the die rollduring a loading portion of a capsule forming cycle, and with thecutting out rims raised during a cutting out portion of a capsuleforming cycle, a valve plate positioned against the valve plate surfaceof said die roll having therein a vacuum chest, an atmospheric pressurechest, and a pressure chest, in such angular position as to draw aplastic strip into the capsule forming cavity and hold the strip in thecavity during a loadin cycle, release the strip in time to eject surplusair before a cover strip is juxtapositioned, and eject the capsule afterits formation, a vacuum lead, an atmospheric vent, and a pressure lead,respectively, to said chests.

5. A sealing roll system for forming soft plastic capsules from plasticstrip which comprises: a cavity die roll, having capsule formingcavities therein, radially movable cutting out rims around said capsuleforming cavities, cam means to position the cutting out rims about evenwith the surface of the cavity die roll when the plastic strip issupplied to the face of the cavity die roll and to force said rimsthrough plastic strip layers during cut out and sealing, a flexiblemetal belt positioned upon and in cutting out relationship with saidrims during a cutting out and sealing portion of the travel of said dieroll, and support rolls for said belt, at least one of which isadjustable to maintain tension in said belt.

6. The method of forming soft gelatin capsules which comprises:supplying a soft gelatin strip to the face of a die roll, formingcapsule forming cavities by localized application of subatrnosphericpressure to areas on one side of said strip, filling the thus formedcavities with the material being encapsulated, tangentially feeding asecond soft gelatin strip into contact with the first strip, retainingthe two strips together by pressure applied over the entire contactingareas of said strips, applying a cutting out and sealing pressure aroundthe peripheries of the filled cavities, while maintaining the holdingpressure over the remainder of the contacting areas, to retain thestrips in position during the application of cutting out and sealingpressure, and separating the thus formed capsules from the remainder ofthe strips.

References Cited in the file of this patent UNITED STATES PATENTS1,970,396 Scherer Aug. 14, 1934 2,387,747 Cowley Oct. 30, 1945 2,546,059Cloud Mar. 20, 1951 2,621,740 Shanley Dec. 16, 1952

